Thermal converter devices, systems and control methods

ABSTRACT

A system is provided for reducing exhaust emissions. The system can comprise a series of chambers, an injector head, and a controller. The controller can maintain desired temperature zones and chemical environments inside the series of chambers, and the chambers and structures inside the system  10  can provide a desired travel path for the air, fuel, and untreated exhaust mixture inside.

RELATED APPLICATIONS

This application claims benefit under 35 U.S.C. § 119(e) to U.S.Provisional Patent Application No. 61/042,665, filed Apr. 4, 2008, whichis incorporated in its entirety by reference herein.

BACKGROUND OF THE INVENTIONS

1. Field of the Inventions

The present application relates to emission reduction devices, systems,and control methods, and more particularly to devices, systems, andcontrol methods for reducing exhaust emissions from a diesel engine.

2. Background of the Inventions

The toxic release into the atmosphere of exhaust emissions fromcompression ignition (“diesel”) engines is a global environmentalproblem and is prevalent in populated areas world-wide. Exhaust emissionreduction of gases, solids, and condensates of diesel-powered systemshave been the subject of both new and retrofit devices and methods.

An internal combustion engine burns hydrocarbon fuel (approximately 85%carbon and 15% hydrogen) in oxygen from incoming air (approximately 20%molecular oxygen and 78% molecular nitrogen). For diesel engines, thecombustion process burns a mass ratio of air-to-fuel generally in arange of 19 under load to more than 40 at idle. This range is lean (fuelpoor) to very lean since the stoichiometric mass (chemically balanced)air-to-fuel ratio is 14.7, stoichiometric being neither fuel rich norfuel poor.

An engine exhaust flow generally consists of CO2, water, nitrogen,oxygen, and pollutants. These pollutants can be the result ofundesirable high temperature and pressure combustion of nitrogen of theengine's incoming air (e.g. NOx) and the incomplete combustion of thehydrocarbon fuel including particulate matter (PM), i.e. soot, unburntand partial hydrocarbons (HC), and carbon monoxide (CO). NOx is ageneral term usually denoting nitric oxide (NO) and nitrogen dioxide(NO2). The emission control strategy for automobiles with a sparkignition engine (“gasoline engine”) generally uses an after treatmentdevice called a three way catalytic converter (TWC) that includes asensor (“lambda sensor”) that measures oxygen in the exhaust streamrelative to ambient levels. The lambda sensor can provide a feedback tothe engine fuel control system in order to maintain a stoichiometricair-fuel ratio. Lambda can refer to the actual air-fuel ratio divided bythe stoichiometric air-fuel ratio. The TWC uses two catalysts foroxidizing CO and HC and a third catalyst for converting NOx to molecularnitrogen (N₂). However for the three catalysts to function properly, thegasoline engine is required to run the combustion process atstoichiometric, that is, the air-fuel ratio must be neither rich norlean in fuel (lambda equal to 1)

Diesel engine exhaust emissions species are different than gasolineengine emissions. For example, diesel engine exhaust emissions includemore air (N₂ and O₂) and PM. Gasoline-fueled spark ignition enginesgenerally have very little PM emissions compared to diesel engines.Diesel engines are always operated lean, and therefore can not use thesame emissions control strategy as used in the automobile exhaustsystem, especially the NOx catalyst due to the high oxygen content ofthe exhaust. Some diesel emission reduction methods use a filter to trapand collect the PM (e.g. soot). The accumulated soot can build up to thepoint of clogging the exhaust system, ultimately resulting in damage tothe engine. The filter must be either routinely replaced or cleaned(often referred to as regeneration) to burn out the soot accumulationbefore the system can be used again without damage to the engine.

The diesel engine emissions of PM and NOx released into the atmosphereare especially a public health problem. Current methods and devicesprocess a subset of pollutants, and require multiple bulky devices to beinstalled. Devices and methods that have been explored are dieseloxidation catalyst (DOC), injection of fuel-borne catalysts, engine gasrecirculation (EGR), selective catalytic reduction (SCR), as well asdiesel particulate filters (DPF). DPF are commonly used to reduce PMsince the efficiency of the filter is good over a range of particlesizes (10 nm to 500 nm). A DPF can be fitted to new engines as well asretrofitted to existing engines, provided that the DPF does not increaseengine exhaust backpressure beyond certain limits.

Practical DPFs have a filter medium consisting of a porous material in awall-flow structure such as a ceramic honeycomb whereby alternate cellends are closed requiring the flow through the fine microporous walls.Other surface-rich media may be sinter filters that are formed as a bagor bellow structures. Yet other types are fiber filters and filterpapers similar to inlet air filters. A consequence of DPF, however, isthat the build-up of accumulated PM and ash (“soot loading”) can impactthe engine as increased back-pressure. Increasing back-pressure can robthe engine of power, increasing fuel usage and ultimately damaging theengine. Additionally, the DPF can trap PM but can not provide reductionsof gases of CO and NOx. To reduce CO and NOx requires more devices suchas DOC to reduce CO and THC, and SCR to reduce NOx.

Only a few technologies such as EGR and SCR have attacked the NOxproblem, with limited operational success. EGR feeds back cooler exhaustinto the hotter combustion to reduce NOx, causing lower temperatures inthe cylinders. Contamination within the engine has resulted in fewer EGRdevices. SCR requires the introduction of urea or ammonia as a reductantin its chamber to chemically process the NOx. SCR requires aninfrastructure to support normal operation. For diesel-poweredtransportation equipment SCR has a number of problems. Theinfrastructure to replace and maintain this in the field is enormous. Inaddition, another device (e.g. filter) must be included in the output,since during the reduction process some of the ammonia can “slip” outinto the atmosphere.

Thermal afterburning has been used as a cogeneration process for boilersand was tried as an after treatment device to reduce hydrocarbonemissions by completing the combustion process. Emissions control ofpollutants such as PM, CO and HC can be burnt to completion, producingCO2 and H2O, but as the temperature is increased to promote burning,some of the molecular nitrogen in the air is converted to NOx (e.g. NOand NO2). In the past, thermal afterburning was tried as an emissioncontrol device to increase the specific residence time at hightemperatures for combusting to completion the exhaust gas constituents,but as described above, this failed to reduce NOx and therefore has hadlimited utility.

SUMMARY OF THE INVENTIONS

In engine applications, including but not limited to those of trucks,construction equipment, stationary generators, railroad locomotives, andmarine vessels, exhaust emissions can consist of harmful pollutants suchas nitric oxides (NOx), PM, CO, and HC. As described above, dieselengines cannot use catalytic converters to eliminate some or all ofthese pollutants, and current technology does not efficiently andaccurately address the problems associated with emissions in suchengines. In particular, current technology does provide for an efficientway to convert and/or burn PM, CO, and HC to carbon dioxide and water,while at the same time reducing nitric oxides in the exhaust. Therefore,an aspect of at least one of the embodiments disclosed here includes therealization that it would be advantageous to have a single system,capable of use with new engines or of retrofitting on old engines,including but not limited to diesel engines, which can efficientlyreduce and/or eliminate the harmful pollutants described above.

Thus, in accordance with at least one embodiment, a system for reducingengine exhaust gas pollutants can comprise a tube assembly comprising aninjector head, a plurality of chambers, at least one of the chamberscoupled to the injector head, and the plurality of chambers furthercomprising at least one component for directing a flow of mixture insidethe tube assembly. The tube assembly can further comprise a dischargeexhaust pipe coupled to one of the chambers, a heat exchanger coupled tothe plurality of chambers, and an untreated exhaust inlet coupled to theheat exchanger. The system can further comprise a fuel flow devicecoupled to the injector head, an air device coupled to the injectorhead, and a controller configured to communicate with the fuel device,the air device, and the injector head.

Thus, in accordance with at least another embodiment, a device forreducing exhaust emission pollutants through combustion processes thatburn hydrocarbon fuel in the presence of air can comprise a plurality ofchambers in communication with an engine exhaust source and a dischargepipe, the plurality of chambers comprising components configured tomanipulate an exhaust flow inside the chambers and form timed heatedchemical environments for the combustion of chemical pollutants.

Thus, in accordance with at least another embodiment, a method ofreducing exhaust gas pollutants in an engine's exhaust can compriseproviding an assembly comprising an injector head, a plurality ofchambers, at least one of the chambers connected to the injector head,the plurality of chambers comprising at least one component fordirecting a mixture of flows inside the tube assembly, a dischargeexhaust pipe connected to one of the chambers, a heat exchangerconnected to the plurality of chambers, an untreated exhaust inletconnected to at least one of the heat exchanger and injector head, and acontroller in communication with the injector head. The method canfurther comprise directing untreated exhaust from the engine to at leastone of the injector head and heat exchanger, directing secondary fueland secondary air into the injector head, igniting the secondary fuel,directing the ignited secondary fuel and secondary air into theplurality of chambers, directing the untreated exhaust from at least oneof the injector head and heat exchanger into the plurality of chambersto form the flow of mixture inside the tube assembly, treating theuntreated exhaust by combusting pollutants in the flow of mixture in theplurality of chambers, cooling the mixture of flow in the plurality ofchambers to reduce nitric oxides mixture of flow, and discharging themixture of flow out the discharge exhaust pipe.

Thus, in accordance with yet another embodiment, a basic control methodfor controlling secondary fuel and secondary air sources in a systemwhich reduces engine exhaust gas pollutants can comprise providing anassembly comprising an injector head, a plurality of chambers connectedto the injector head and a discharge exhaust pipe, an untreated exhaustinlet connected to the plurality of chambers, a controller incommunication with the injector head, at least one ambient sensor, andat least one temperature sensor adjacent the exhaust inlet and at leastone temperature sensor adjacent the discharge exhaust pipe. The methodcan further comprise collecting temperature, humidity, and pressure datafrom the at least one ambient sensor and at least one temperaturesensors, comparing the obtained temperature data with predeterminedvalues of temperature set points in the controller, and based on the setpoints, determining a temperature error, calculating a desired compositelambda, the composite lambda representing a total air and fuel ratioinside the plurality of chambers, separating the desired compositelambda and producing secondary fuel and secondary air commands whichdirect secondary fuel and secondary air into the plurality of chambersto be mixed with untreated exhaust, and monitoring the dischargetemperature of the mixture at the discharge pipe and modifying thesecondary fuel and secondary air commands.

Thus, in accordance with yet another embodiment, a dynamic controlmethod for controlling secondary fuel and secondary air sources in asystem which reduces engine exhaust gas pollutants can compriseproviding an assembly comprising an injector head, a plurality ofchambers connected to the injector head and a discharge exhaust pipe, anuntreated exhaust inlet connected to the plurality of chambers, acontroller in communication with the injector head, at least one ambientsensor, and at least one temperature sensor adjacent the exhaust inletand at least one temperature sensor adjacent the discharge exhaust pipe.The method can further comprise collecting temperature, humidity, andpressure data from the at least one ambient sensor and at least onetemperature sensors, comparing the obtained temperature data with apre-loaded table of temperature set points in the controller, and basedon the set points, determining a temperature error, calculating adesired composite lambda, the composite lambda representing a total fueland air ratio inside the assembly, adjusting the rate of rise and fallfor the desired composite lambda in order to minimize potentialovershoot or undershoot of a desired discharge temperature at thedischarge exhaust pipe, adjusting the desired composite lambda tocompensate for steady-state errors, separating the desired compositelambda and producing secondary fuel and secondary air commands whichdirect secondary fuel and secondary air into the plurality of chambersto be mixed with untreated exhaust, and monitoring the dischargetemperature and modifying the secondary fuel and secondary air commands.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present embodiments willbecome more apparent upon reading the following detailed description andwith reference to the accompanying drawings of the embodiments, inwhich:

FIG. 1 is a schematic illustration of an embodiment of a thermalconverter system.

FIG. 2 is a schematic illustration of an embodiment of an injector headof the system of FIG. 1.

FIG. 3 is a schematic illustration of an embodiment of a converter tubeassembly of the system of FIG. 1.

FIG. 4 a is a front elevational view of an embodiment of a helicalstator used in the injector head.

FIG. 4 b is a front elevational view of an embodiment of a helicalstator used in the converter tube assembly.

FIG. 5 a is a schematic top view of an embodiment of a heat exchanger ofthe system of FIG. 1.

FIG. 5 b is a schematic side view of the heat exchanger of FIG. 5 a.

FIG. 6 is a schematic illustration of another embodiment of a thermalconverter system.

FIG. 7 is a schematic illustration of an embodiment of thermalcontroller interface.

FIG. 8 is a flow chart of an embodiment of controller functions.

FIG. 9 is a flow chart of an embodiment of emissions guidance andcombustion control.

FIG. 10 is a flow chart of an embodiment of a basic control mode for thecontroller.

FIG. 11 is a flow chart of an embodiment of a dynamic control mode forthe controller.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Thermal ConverterSystem

With reference to FIG. 1, an embodiment of a thermal converter system 10can include a tube assembly 12. The tube assembly 12 can comprise aninjector head 14, an assembly 16 of connected chambers and/orpassageways, and an exhaust pipe 18. The tube assembly 12 can furthercomprise insulation material, an outer shell, and/or mounting hardware,which are not shown. In some embodiments, the tube assembly 12, or partsof the tube assembly 12, can comprise a right-circular long metal tube.

The system 10 can further include a thermal controller 20, fuel device22, and air device 23, each of which can be in communication with and/orconnected to the tube assembly 12. In some embodiments, the fuel device22 can comprise a fuel flow rate controller. In some embodiments, theair device 23 can comprise an air blower or blowers. The system 10described herein can be used, for example, to treat untreated exhaustgas which exits from an engine, and to reduce emissions of harmfulpollutants such as particulate matter (PM) and oxides of nitrogen (NOx)in the exhaust gas.

With continued reference to FIG. 1, untreated exhaust from an engine(e.g. diesel engine) can be directed into the converter tube assembly 12through an untreated exhaust inlet 24. The untreated exhaust can firstbe heated to an elevated temperature inside the tube assembly 12, andthen mixed with a burning secondary air and fuel mixture inside theconverter tube assembly 12. The burning secondary air and fuel mixtureinside the tube assembly 12 can be a combination of secondary air andsecondary fuel directed into the tube assembly 12 by the fuel device 22and air device 23, and ignited inside the injector head 14. In someembodiments, the secondary fuel can come from the same fuel source thatis powering the engine. In other embodiments, the secondary fuel can bederived from an entirely separate source.

With continued reference to FIG. 1, the controller 20 can be powered bya power source and/or electrical interface, and can be in communicationwith the fuel device 22, air device 23, and injector head 14. The fueldevice 22 can control the amount of secondary fuel that enters theinjector head 14 of tube assembly 12, and can have a fuel source andreturn line or lines. The air device 23 can control the amount ofsecondary air that enters the injector head 14 of tube assembly 12, andcan have an air source. For example, once the thermal controller 20determines the amount of secondary air and fuel to be delivered by thefuel device 22 and air device 23, secondary air and fuel can bedelivered to the injector head 14, and the mixture can be ignited.

Adding a burning secondary fuel and air mixture to an untreated heatedexhaust inside the tube assembly 12 can facilitate completion ofchemical conversion processes inside the tube assembly 12, and reducethe amount of pollutants that exit through the exhaust pipe 18. Suchpollutants can include, but are not limited to, NOx by-products,unburned compounds including paraffinic, naphthenic, and aromatichydrocarbons, partially-burned combustion products of carbon monoxideand hydrocarbons including aldehydes and keytones, and thermaldecomposition products including particulate matter (i.e. elemental andorganic carbon, and polycyclic hydrocarbons).

With reference to FIGS. 1 and 2, the injector head 14 can include a fuelsupply inlet 26 and fuel return outlet 28. Secondary fuel exiting thefuel device 22 can enter the injector head 14 through the fuel supplyinlet 26, and can then enter a fuel nozzle 30, which can be bracketed inplace inside the injector head 14. The nozzle 30 can be a pressure feednozzle which has a high pressure side at constant pressure and a returnside which allows secondary fuel to be returned back to the fuel device22 via the fuel return outlet 28. The nozzle 30 can provide a fine spraypattern of secondary fuel as the secondary fuel is mixed with secondaryair under pressure. The fuel nozzle 30 can spray the secondary fueltowards an igniter 32, and unused secondary fuel can return from thefuel nozzle 30 to the fuel device 22 via the return outlet 28. Otherembodiments may provide spray patterns using other nozzle arrangementssuch as an air atomizing nozzle and/or multiple nozzle configurations.

With continued reference to FIGS. 1 and 2, the injector head 14 can alsoinclude an air supply inlet 34. Secondary air exiting the air device 23can enter injector head 14 via air inlet 34. The secondary air can mixwith the secondary fuel spray, and the mixture can ignite under theigniter 32.

With continued reference to FIGS. 1 and 2, the injector head 14 can alsoinclude an engine exhaust tap and inlet 36. In some embodiments, aportion of the untreated exhaust from inlet 24 can be directed throughthe exhaust tap and inlet 36. The untreated exhaust entering theinjector head 14 through inlet 36 can be mixed with the secondary fueland secondary air, and ignited under the igniter 32.

With reference to FIGS. 1, 2, and 4A, the injector head 14 can includean air/exhaust deflector 37 and/or a helical stator 38. The air/exhaustdeflector 37 can be shaped so as to deflect incoming air and untreatedexhaust in a desired direction through the injector head 14, as can thehelical stator 38.

With reference to FIG. 4A, the helical stator 38 can have a solid rimdam 40, solid angled vanes 42, and vane openings 44. The helical stator38 can be positioned inside the injector head 14 such that itfacilitates rotation of any air, fuel, and/or exhaust moving through theinjector head 14. In some embodiments, the helical stator 38 can have nomoving parts. An opening 44 in the central portion of the helical stator38 can provide room for the fuel supply inlet 26 and fuel return outlet28, as shown in FIG. 2. Other sizes, shapes, and configurations ofstator 38 can also be used.

As the swirling mixture of secondary fuel, secondary air, and/or exhaustbegins to rotate due to the helical stator 38, the mixture can beignited by the igniter 32 in injector head 14, and start to burn. In atleast one embodiment, the igniter 32 can be activated by the controller20 until a flame detector detects heat, at which point the igniter 32can be shut off. As the mixture of secondary fuel, air, and/or exhaustbegins to burn, the mixture can be directed into the chambers ofassembly 16.

With continued reference to FIG. 2, the length and diameter of theinjector head 14 can vary. For example, in at least one embodiment, thelength and diameter can be determined by the system 10's maximum exhaustmass flow rate. In at least one embodiment, the injector head 14 can bean elongated right-circular metal tube. Other sizes, shapes, andconfigurations are also possible.

With reference to FIG. 3, and as described above, the tube assembly 12can comprise an untreated exhaust inlet 24. The incoming flow ofuntreated exhaust can be split, such that a first portion is directed tothe injector head 14 through 36 as described above, and a second portionis directed to a heat exchanger 46 located in the assembly 16. In atleast one embodiment, the diameter of the untreated exhaust inlet 24 canbe sized based on the diameter of the exhaust pipe 18, and the maximumexhaust volumetric flow rate. In at least one embodiment, 20% of theuntreated exhaust from inlet 24 can be directed to the injector head 14,and 80% to the heat exchanger 46. Other percentages are also possible.

With continued reference to FIG. 3, the second portion of the untreatedexhaust can flow down a passageway 48 towards the heat exchanger 46. Inat least one embodiment, the heat exchanger 46 can comprise a series oftube packets, including at least one catalyst coated heat exchanger tubepacket 50. The flow of untreated exhaust can move through tubes in thetube packet 50 (see arrows in FIG. 3) and continue out the bottom of thepacket 50 into another packet in a series of tube packets. The flow ofuntreated exhaust can continue through this series of packets until itreaches, for example, an uncoated tube packet 52. As the untreatedexhaust exits uncoated tube packet 52, it can flow into a passageway ofa pre-heat jacket 54. The pre-heat jacket 54 can comprise any type ofstructure which provides a pathway for the exiting untreated exhaustfrom the heat exchanger 46 to a mixing chamber 56 in the assembly 16. Asillustrated in FIG. 3, the untreated exhaust can move through thepre-heat jacket down assembly 16 and enter the mixing chamber 56.

With continued reference to FIG. 3, the inner shell of mixing chamber 56can have a pattern of openings 58 which allow the flow of untreatedexhaust in the pre-heat jacket to enter the inside of mixing chamber 56.For example, the mixing chamber 56 can comprise a plurality of openingson an inner shell, and an outer shell which forms a passageway to theopenings. In at least one embodiment the openings 58 are round holes.Other embodiments can entail slots of various lengths to facilitateand/or force a particular flow direction or pattern into the mixingchamber 56. In some embodiments, the shape, size, and number of theopenings 58 can vary. In some embodiments, the mixing chamber 56 can bea right-circular metal tube. In some embodiments, the mixing chamber 56can include an inlet from the injector head 14 which has a diametersized based on the exhaust pipe 18 diameter, maximum exhaust volumetricflow rate, and/or allowable backpressure in the system 10.

Once inside mixing chamber 56, the rotating, burning, secondary fuel,secondary air, and/or untreated exhaust mixture arriving from injectorhead 14 can be mixed in a turbulent fashion with the untreated exhaustentering through holes 58. The untreated exhaust can be diluted insidethe mixing chamber 56, and the flow velocity and turbulence on theinside of mixing chamber 56 can thoroughly mix the constituents.

The mixing chamber's length-to-diameter ratio can be kept on the orderof one so that any gas film conductance is overridden by turbulence,enhancing heat transfer to the incoming untreated exhaust. In someembodiments the mixing chamber 56 is connected to the injector head 14,and the length-to-diameter ratio of an inner tube (e.g. shell) of themixing chamber is less than three. The mixing chamber's diameter andinternal overall flow resistance can also be sized to maintain a backpressure that substantially matches the operating characteristics of theparticular engine and/or application the system 10 is working on at thetime.

With reference to FIGS. 3 and 4 b, as the turbulent mixture of secondaryfuel, secondary air, and untreated exhaust moves through the mixingchamber 56 and into a combustion chamber 60, the mixture can encounterat least one of a second type of helical stator 62. The helical stator62 can have a different configuration from that of helical stator 38described above. For example, the helical stator 62 can comprise a thindisk with an outer solid rim dam 64. The disk can have a diameter equalto the diameter of the chamber wall in the combustion chamber 60. Thehelical stator 62 can have a number of solid angled vanes 66 alongequally spaced radials that extend from a small solid center stop 68 tothe rim dam 64. The helical stator 62 can allow translating flow to passthrough vane openings 70 while still imparting a rotational component tothe traveling mixture as it flows over the vane surfaces. The helicalstator 62 can have no moving parts. Other sizes, shapes, andconfigurations for the helical stator 62 are also possible.

In some embodiments, the combustion chamber 60 can have a diameter andlength compatible with the mixing chamber 56. As solids in the mixtureburn in the combustion chamber 60, the releasing gases can find theirway out through the helical stator's vane openings 70, and move furtheralong in the assembly 16. Within the combustion chamber 60, the mixtureof secondary fuel, secondary air, and untreated exhaust can combust athigh temperatures, and a majority of the remaining chemical energy ofthe mixture can be released, oxidizing some compounds in the mixture,but increasing NOx formation. The helical and rotational motion of themixture caused by the stators 38 and 62 can create a coil-like patternas the mixture travels downstream through the combustion chamber 60.

The centrifugal effect of this turbulent mixture rotation in thecombustion chamber 60 can cause the more massive constituents in theturbulent mixture to be thrown towards the chamber wall. Since theheavier particles have a translating component, the heavier particlescan hit the rim dams 64 of helical stators 62. The helical stator rimdams 64 can deflect the passage of these particles in the turbulentmixture, increasing their dwell time within the combustion chamber 60.Thus, the turbulence induced by the helical stators 62 can cause alonger residence time (i.e., dwell time) in the combustion chamber 60.

As the helical coil of flow tightens the radial temperature distributionpattern can generally become more pronounced. For example, thedistribution pattern can be higher at the core of the flow and lower atthe combustion chamber's wall. After moving through the combustionchamber 60, the mixture can enter a reaction chamber 72. The reactionsinside the reaction chamber 72 can sustain the combustion of anyremaining hydrocarbon in the mixture.

With reference to FIGS. 3 and 4 b, as the flow of mixed and combustedgases (multi-phase fluid components) continues on through the reactionchamber 72, the flow can encounter another helical stator 62. In oneembodiment, a helical stator 62 can form a border between the reactionchamber 72 and heat exchanger 46. The helical stator 62 at this locationcan be smaller in diameter than that of the previous helical stator orstators 62 in the combustion chamber 60, but can still include a rim dam64, vanes 66, stop portion 68, and openings 70.

With reference to FIGS. 1 and 3, the dwell time of the mixture withinthe converter tube assembly 12 can be dependent upon the overall lengthof the chambers inside the assembly 16, as well as the helical statorspacing inside the assembly 16. For example, the spacing of the stators38 and/or 62 can facilitate a steady helical flow of the mixture withinthe tube assembly 12 and process the multi-phase fluid components (i.e.mass-dependent solid particles and vapors) for complete burning.

For a given translational velocity with no frictional or turbulentlosses in the tube assembly 12, there can be a preferred spacing ofhelical stators. For example, with a given design of helical stators(same number of vanes, equally spaced vanes, vane opening angles, andradial dimensions of rim dam and stop) the helical stators can bepositioned in a constant diameter chamber at a characteristic length(preferred distance between stators) such that the stream of rotatingmulti-phase fluid components in the mixture maintains a rotation similarto a spinning bullet traveling down a rifled barrel. In other words, fora given tube length, the helical stators can be spaced apart in such away that the flow rotates at a minimum up to one complete full rotationin between each helical stator.

This characteristic length can be dependent upon, for example, the massbulk density of the mixture flowing through the given chamber, theinitial flow translational velocity, and the length and number of vanes.By altering these factors, different characteristic lengths can beachieved, and the helical stators can be spaced apart so as to createpreferred dwell times. For example, in at least some embodiments, thehelical stators can be spaced apart such that one-half of a fullrotation occurs between each stator, or some other fraction or multipleof a full rotation. This can facilitate turbulence within the chamber,decelerating the flow components and resulting in increased mixing anddwell time as compared to a chamber without any stators. In someembodiments, the dwell times for particulate matter inside a singlechamber can range from 20 milliseconds to 200 milliseconds, depending onthe chamber temperature and incoming exhaust volumetric flow rate. Insome embodiments, the total flow of mixture inside the tube assembly 12can be held between 50 and 1000 milliseconds. Other ranges for dwelland/or holding times are also possible.

The helical stators described herein also can affect the backpressurefelt within the converter tube assembly 12. By varying the geometry(e.g. length and surface area of rim dams and stops) and positioning ofthe helical stators, the pressure within the tube assembly 12 can bealtered or adjusted as desired.

With reference to FIG. 3, in some embodiments the tube assembly 12 cangenerally comprise an ignition zone 74 near the injection head 14, adilution zone (e.g. mixing chamber 56 and combustion chamber 60), and acooling zone (e.g. reaction chamber 72 and heat exchanger 46). In atleast one embodiment, an insulating shell (not shown) can be used tocover the tube assembly 12. The insulating shell can, for example,facilitate preheating of untreated exhaust as it flows from inlet 24towards the mixing chamber 56.

NOx reduction within the converter tube assembly 12 can be accomplishedvia cooling and catalytic conversion. Cooling can occur through the useof a device such as the heat exchanger 46. With continued reference toFIG. 3, helical stators 62 can bound the heat exchanger 46 on eitherside, isolating the heat exchanger 46 into its own chamber to providecontinued residence time within the tube assembly 12 for the burningmixture. In some embodiments, the helical stators 62 bordering the heatexchanger 46 can provide less resistance to the mixture than the helicalstators 62 found in the combustion chamber 60. This can be accomplished,for example, by narrowing the size of the vanes 66, decreasing the sizeof the stop 68, increasing the size of any openings 70, and/ordecreasing the size of the rim dam 64. This reduction in resistance canenhance the flow rate of the mixture and help it to overcome anyresistance due to the friction it may encounter from, for example, tubesin a heat exchanger 46, as well as from a smaller diameter of the heatexchanger as compared to the reaction chamber.

With reference to FIGS. 5A and 5B, a heat exchanger 46 can comprise acounter flow device whereby the incoming untreated exhaust flow from theinlet 24 can enter at opening 78 and initially follow a path through apacket 50 of tubes 80 which are coated with catalyst. In someembodiments, the heat exchanger 46 can be capable of sustained operationwithout significant degradation to any catalytic coatings.

With reference to FIG. 5B, containment plates 82 can inhibit flow sothat the stream of untreated exhaust flows out the tubes 80, into a nextpacket of tubes, and out openings 84. The untreated exhaust can movethrough a plurality of either coated and/or uncoated tubes, finallyentering openings 86 and then exiting openings 88 and into pre-heatjacket 54. Packet walls 90 can be used to separate out the packets oftubes. The number of tubes and tube packets needed to heat the incominguntreated exhaust to a preferred temperature while minimizing theuntreated exhaust backpressure can be a function of the overall pressuredifference, gas velocity, and tube packet temperature environment.

In at least one embodiment, the heat exchanger 46 tube packets can raisethe untreated exhaust temperature by 350° F. (450 K), deriving theirsource of heat primarily from the combustion chamber 60. Othertemperature increases or ranges are also possible. The heat exchanger 46can thus provide preheating to the incoming untreated exhaust from inlet24 to decrease the required secondary fuel usage from fuel device 22.While the illustrated embodiment shown in FIG. 5B directs the flow ofuntreated exhaust to the downstream heat exchanger packet 80, in otherembodiments the inlet 78 to the heat exchanger 46 can be locatedelsewhere.

With continued reference to FIG. 5B, an example heat exchanger 46 can bea packet consisting of 100 heat-resistant tubes each of one-eighthdiameter and 5 inches in length. To raise the temperature of theuntreated exhaust by 350° F. can require, for example, 10 packets for anexhaust inlet 24 of 2 inches in diameter. Other numbers of tubes andtube size and diameter are also possible. The counter flow methodillustrated in FIGS. 5A and 5B can provide a higher untreated exhaustgas temperature as the untreated exhaust gas enters the mixing chamber56 as compared to a parallel flow. In some embodiments, a parallel flowmethod can be used in the heat exchanger 46 to reduce the cross flowtube temperature and/or improve catalytic conversion.

In at least one embodiment, the cross-sectional shape of the heatexchanger 46 can be rectangular to make maximum use of the tube lengths.Other cross-sectional shapes can also be implemented, including acircular cross-section. As described above, the heat exchanger 46 tubescan derive their source of heat from the combustion chamber 60 flowoutput as the mixture of secondary fuel, secondary air, and/or exhaustdischarges from the combustion chamber 60 towards the exhaust pipe 18.The flow output of the heat exchanger 46 tubes can be channeled towardthe mixing chamber openings 58. This method of preheating the untreatedexhaust can facilitate reduction of secondary fuel usage.

Referring to FIGS. 3 and 5B, as the mixture of burning secondary fuel,secondary air, and/or exhaust moves through the tube assembly 12 towardsthe exhaust pipe 18 and impinges on the catalytic coated tubes of theheat exchanger 46, the NOx in the mixture can disassociate into nitrogenand oxygen. By maintaining a low oxygen environment, as well as a coolerenvironment in the heat exchanger 46, NOx reduction can be enhanced.

In some embodiments, heat-resistant metal tubes can be used in the heatexchanger 46. As described above, these tubes can be coated and/oruncoated. In some embodiments, poison-resistant lean NOx catalystcoatings can be used. Coatings can be selected to reduce NOx. Thecatalyst coatings can, in some embodiments, preferably comprise a metalzirconium phosphate such as barium, cesium or silver. (Reference ismade, for example, to U.S. Pat. No. 6,407,032 B1, issued Jun. 18, 2002to Labarge et al., which describes a poison resistant lean NOx catalyst)Embodiments can vary according to application.

With continued reference to FIG. 3, as the mixture travels through theheat exchanger 46, its high temperature gas can impart heat to theincoming untreated exhaust gas flowing through the tubes in heatexchanger 46. The heat exchanger 46 can thus facilitate cooling of themixture, as well as add additional residence time. In at least oneembodiment, the heat exchanger 46 can be sized to reduce the backpressure felt by the exhaust inlet 24. Other embodiments can includeincreased cross sectional areas and lengths of the heat exchanger 46 tofurther enhance the heat transfer capabilities and reduce pressuredifference.

The reaction chamber 72 can complete the high-temperature combustiontransition phase prior to introducing the mixture into the cooler flowzone of the heat exchange 46. The gas to gas heat transfer process ofthe heat exchanger 46, as well as the heat exchanger's length canfacilitate cooling of the flow of mixture in the tube assembly 12. Asdescribed above, by cooling the heated mixture as the mixture movesthrough the heat exchanger 46, some or all of the NOx componentsremaining in the mixture can be reduced and converted into nitrogen andoxygen before leaving through exhaust pipe 18.

In some embodiments, other cooling methods besides that shown in FIGS.3, 5A, and 5B are also possible. For example, air from the blower 23 canbe directed not only into the injector head 14, but also along theoutside of one or more of the chambers in the tube assembly 12. Withreference to FIG. 6, in an embodiment of another thermal convertersystem 110, air can be directed to a jacket, or shell 76 along theoutside of the reaction chamber 72. The untreated exhaust inlet 24 canbe located upstream of the shell 76, such that as a mixture of secondaryfuel, air, and exhaust is burned, it is cooled in part by the air movingthrough shell 72, and NOx can be reduced.

In some embodiments, the chamber length of the reaction chamber 72 canbe at least twice the chamber's diameter such that the heat transferacross the chamber wall is established by the combustion products on theinside of the chamber and any air coolant flow on the other side. Thiscan facilitate cooling of the combustion products inside the reactionchamber 72 and reduction of NOx.

The tube assembly 12 and thermal converter systems described above canbe used with a variety of engines and/or applications, including but notlimited to diesel engines using diesel fuel or biodiesel blends. Asdescribed above, the thermal tube assembly 12 can use a series ofchambers and helical stators. While the embodiment illustrated in FIGS.1-4 uses five helical stators, other embodiments can use differentnumbers and/or configurations of helical stators. Additionally, whilethe embodiment illustrates a mixing chamber, combustion chamber, andreaction chamber, other numbers of chambers can also be used.

As described above, combined secondary air, secondary fuel, anduntreated exhaust can be directed through the tube assembly 12. Thechambers and helical stators inside can provide a travel path in whichcontrolled axial and radial temperature distributions provide desirablereaction times that are mass dependent. Thus, the tube assembly 12 andsystem 10 described above can utilize timed heated chemical environments(e.g. mixing chamber 56, combustion chamber 60, reaction chamber 72, andheat exchanger 46) to promote selected reactions and reduce unwantedemissions. A chemical atmosphere or atmospheres can be provided insidethe tube assembly 12 which cause chemical changes by inducing oxidationand/or reduction reactions, even in the presence of the engine exhuast'sexcess air. These chemical environments can range in temperature. In atleast one embodiment, for example, the temperatures in theabove-mentioned chambers can range from 800° F. (700 K) to 2300° F.(1533 K). Other ranges and temperatures are also possible, althoughstaying below 2800° F. (1810 K) can be preferred due to the onset ofrapid NO formation reactions. Chamber temperature zones can be providedfor thermal mixing, high temperature combustion, heat exchanger cooling,and/or discharge cooling. In some embodiments, the tube assembly 12 caneliminate approximately 89 percent of all particulate matter.

The tube assembly 12 and system 10 described above can be usedadvantageously, for example, to reduce and/or eliminate nitrogen oxides(NOx, the compounds of nitric oxide NO and nitrogen dioxide NO₂),particulate matter (PM, carbon “soot” that is in the solid state),unburned hydrocarbons including paraffins, olefins, and aromatichydrocarbons, and partially-burned combustion products such as carbonmonoxide (CO) and hydrocarbon substances including aldehydes, ketones,and carboxylic acids. The system 10 can, for example, be used on newengines, retrofitted onto old engines, or be used with other sources ofuntreated exhaust. In some embodiments, the system 10 can be retrofittedonto an existing automobile, such as a diesel engine truck.

Controller and Systems Control

With reference to FIGS. 1-7, the controller 20 can comprise, forexample, an electronic control unit comprising a microprocessor. Thecontroller 20 can be in communication with a number of sensors locatedthroughout the tube assembly 12 and system 10, including but not limitedto sensors which monitor the discharge temperature of the exhaust comingout of exhaust pipe 18, the oxygen level of the exhaust coming out ofthe exhaust pipe 18, the temperature of the untreated exhaust as itenters through inlet 24, the oxygen level of the untreated exhaust as itenters through inlet 24, the ambient temperature outside the tubeassembly 12, the ambient humidity outside the tube assembly 12, and thetemperature of a shell surrounding tube assembly 12.

The controller 20 can be configured to monitor conditions of the system10 via the sensors described above, and to maintain a predetermineddischarge temperature at the exhaust pipe 18. For example, thecontroller 20 can estimate the remaining fuel and oxygen levels of theincoming untreated exhaust at inlet 24, as well as the fuel and oxygenlevels of the tube assembly's outgoing discharge at exhaust pipe 18, andthen adjust the secondary fuel (from fuel device 22) and secondary air(from air device 23) to maintain a predetermined discharge temperatureor temperatures at the exhaust pipe 18. These predetermined temperaturepoints can provide the most favorable reduction of pollutants, such asNOx, while minimizing secondary fuel and secondary air usage.

Additionally, the controller 20 can be configured to monitor conditionsof the tube assembly 12, and to maintain a predetermined air/fuel massratio inside the tube assembly 12. By maintaining a predeterminedair/fuel mass ratio, the reactions occurring in the chemicalenvironments (i.e. chambers), as well as the resultant emissionreduction, can be controlled.

With reference to FIG. 7, and as described above, the controller 20 cancommunicate with at least one exhaust gas sensor 202, at least oneambient sensor 204, and at least one discharge sensor 206. The at leastone ambient sensor 204 can include a sensor which senses the temperatureof a shell surrounding the tube assembly 12.

With continued reference to FIG. 7, the controller 20 can have a powerinterface and/or source 208 for starting and stopping the controller 20.The controller 20 can begin to function when a start command isprovided. The start command can initiate an orderly power up of thecontroller and a start sequence of the controller 20 logic. Thecontroller 20 can shut down safely when a stop command is received.

The controller 20 can monitor and control the air device or devices 23,or other cooling sources. The controller 20 can communicate with theigniter 32 in injector head 14, and can monitor and control fuel device22. The fuel device 22 can include a fuel valve, which can be turned offand on to dispense appropriate amounts of fuel based on a signal orsignals from the controller 20. A maintenance and data logging interface210 can provide a self-test function, data table uploads, and datalogging downloads. In some embodiments, further auxiliary inputs andauxiliary flow controls can be used. For example, in some embodiments,the controller 20 can include a data interface which monitors and/ortakes into account engine rpm and/or throttle position.

With reference to FIG. 8, in at least one embodiment the thermalcontroller 20 functions can be performed using a sequence control 212,emissions guidance 214, and combustion control 216.

Sequence control 212 can provide for the overall orderly startup,employment, and safe shutdown of the controller 20 and system 10. Thesequence control 212 can comprise a maintenance control 218, and a powerup/restart control 220. A mode initialization control 222 can determinewhich mode (e.g. a basic or dynamic mode) the system is to operate inwhen controlling the emissions level of the engine exhaust. Thedetermination of what mode to operate in can be based, for example, uponwhich data tables have been uploaded into the controller 20.

The sequence control 212 can further comprise a normal operation control224 and shutdown mode control 226. The normal operation control 224 andshutdown mode control 226 can facilitate an optimal emissions reductionfor a given embodiment and provide proper ignition 32 of the fuel sprayin FIG. 2. Abnormal shutdown 228 can be a safe-fail shutdown controlwhereby secondary fuel and secondary air sources from the fuel device 22and air device 23 are secured and/or shut off, minimizing an unsafecondition due to residual fuel which may be in the tube assembly 12.

With continued reference to FIG. 8, emissions guidance 214 can providefor either a basic mode operation 230 or a dynamic mode of operation232. In the basic mode of operation 230, a minimum set of data and/orsensor information can be used to economically provide a steady-stateresponse. The basic mode of operation 230 can use temperaturedifferences at the input and output of the system 10. For example, thebasic mode can use temperature data from sensors 202 and 206 at theexhaust inlet 24 and at exhaust pipe 18, to control the amount ofsecondary fuel and secondary air that is directed into the tube assembly12.

The dynamic mode of operation 232 can respond to transient conditionswhich result from the system's changing load conditions. Changing loadconditions normally cause a change in exhaust gas composition, includingchanges in pollutants. The dynamic mode of operation 232 can efficientlyrespond to changing fuel and air in the untreated exhaust streamentering inlet 24. This dynamic response can result in using lesssecondary fuel and secondary air as compared to the basic mode, therebyresulting in better fuel economy for the system 10.

With continued reference to FIG. 8, the combustion control 216 cancomprise an air control 234. As described above, the controller 20 cancommunicate with the air device or devices 23, or other cooling sources,to control the amount of secondary air that is directed into theinjector head 14, as well as control any air which may be moving alongthe outside of the tube assembly 12 to aid in heat exchange.

The combustion control 216 can comprise a fuel control 236. As describedabove, the controller can communicate with the fuel device 22 to controlthe amount and rate of secondary fuel delivery which is directed intothe injector head 14.

The combustion control 216 can further comprise an AFR (air to fuelratio) control 238. The AFR control 238 can, in combination with thefuel control 236 and air control 234, control the air to fuel ratio ofthe secondary air and secondary fuel directed into the injector head 14,and consequently, the tube assembly 12.

The combustion control 216 can further comprise a thermal control. Asdescribed further herein, the thermal control 240 can further controlthe amount of secondary fuel and secondary air entering tube assembly12. In some embodiments, the combustion control 216 can further compriseauxiliary controls 242.

With reference to FIGS. 9-11, emissions guidance and combustion controlare shown in further detail. FIG. 9 schematically illustrates anembodiment of the emission guidance 214 and combustion control 216, asutilized in the controller 20. FIG. 10 illustrates an embodiment ofcommands and decisions made by the controller 20 during a basic mode ofoperation 230, and FIG. 11 illustrates an embodiment of commands anddecisions made by the controller 20 during a dynamic mode of operation232.

With reference to FIGS. 9 and 10, and specifically to operation block244 in FIG. 10, in a basic mode of operation 230, the controller 20 canfirst monitor the environment of the system 10. The environment can bemonitored via the ambient pressure, humidity, and temperature sensors204, including a tube assembly 12 shell temperature sensor as describedabove.

With reference to operation block 246, the controller 20 can thencollect information about the temperature of the untreated exhaust atinlet 24 from sensor 202, as well as the temperature of the exhaustbeing discharged out exhaust pipe 18 from sensor 206.

When an engine is running at a given load, the incoming untreatedexhaust will generally have a temperature related to the load (forexample 2-cycle and 4-cycle diesel engines each generally show a linearincrease in exhaust temperature as a function of percent of full load,though each have a different rate of increase). Ideally, for a givenengine load, the discharge temperature should be within a certain range,indicating that hydrocarbon pollutants have been burned off, and NOx hasbeen reduced.

Based on the temperature readings from the sensors described above,particularly that of the incoming untreated exhaust sensor, thecontroller 20 can get an indication of the engine load. Based on thisindication and the values obtained from the other sensors, and withreference to operation block 248 in FIG. 10, the controller 20 can thencompare the temperature values it reads from the sensors with apre-loaded table of temperature set points. These temperature setpoints, along with information about the temperature and construction ofthe tube assembly 12 shell, can be used to determine a temperature erroras follows:

Ktube-1*((Tdischarge−T set point one)−(Texhaust−T set point 2)), whereKtube-1 is a function of shell construction and temperature, and thetemperature set points are derived from uploaded temperature tables inthe controller 20.

The composition of remaining fuel in the untreated exhaust, along withsecondary fuel and secondary air (introduced from fuel device 22 and airdevice 23) can produce a composite temperature environment inside thetube assembly 12. Based on the temperature error obtained above, andwith reference to operation block 250 in FIG. 10, the controller 20 canuse a composite lambda function to calculate a desired composite lambda.

Similar to the industry of modern gasoline engines with three-waycatalytic converters, lambda in general can be a desired air-fuel ratiodivided by the stoichiometric air-fuel ratio for a given application.Therefore, a lambda equal to one can be an air-fuel mixture that isneither rich nor lean. Composite lambda, as described herein, can be alambda which relates to the total air and total fuel in the tubeassembly 12. Thus, it can be a composite of the secondary air, secondaryfuel, and any air and fuel in the untreated exhaust. The desiredcomposite lambda can be a value which can help ensure that the dischargetemperature at exhaust pipe 18 is within a predetermined range, and thatthe pollutants in the untreated exhaust (including NOx) are beingconverted appropriately into their less harmful forms.

Based on the information it has from the sensors described above, thecontroller 20 can calculate a desired composite lambda that will providea chemical environment which will complete the combustion process at aminimum temperature and maximum use of oxygen. Such an environment canbe ideal in that it requires as little secondary fuel as possible, whilestill completing the combustion processes desired.

With continued reference to FIGS. 9 and 10, and with particularreference to operation block 252 of FIG. 10, in an air-fuel controlportion of combustion control 216, the controller 20 can use alambda/AFR function to separate the composite lambda value fromoperation block 250 into secondary fuel and secondary air values neededto maintain a desired composite lambda in the tube assembly 12.

With reference to operation block 254 of FIG. 10, the separatedsecondary fuel and secondary air values can be then be communicated toinitial fuel and initial air command functions that use feedback fromfuel device 22 and air device 23, for example, to produce F′ command andA′ command signals (corresponding to secondary fuel and secondary aircommands, respectively).

With continued reference to FIGS. 9 and 10, and in particular tooperation block 256 of FIG. 10, in the thermal control portion ofcombustion control 216, the secondary fuel and secondary air commandscan be fed to a thermal control function that watches over the operationto guard against runaway commands and runaway temperatures. For example,the controller 20 can build a temperature profile of the system 10 inits environment while power is applied to controller 20, as well asbased on the controller's last use (e.g. in case the controller 20 isexperiencing multiple short periods of on-off use). Since the secondaryair-fuel ratio can be increased by either an increase in secondary airor a decrease in secondary fuel, the controller 20 can be configured towatch and see what happens when a command is given.

For example, and with continued reference to decision block 256 in FIG.10, the controller 20 can monitor the discharge temperature at exhaustpipe 18, as well as other sensors, to determine if appropriate changesare occurring (e.g. if the system 10 is operating within the desiredtemperature set points), or if there is any type of temperature runaway.

With reference to operation block 258, if changes are needed to thesecondary fuel and/or secondary air commands, a change direction logiccan calculate appropriate changes and modify the secondary fuel, Fcommand, and secondary air command, A command. Because the controller 20is using only two temperatures (untreated exhaust temperature anddischarge temperature), but there are four variables (secondary fuel,secondary air, fuel in the untreated exhaust, air in the untreatedexhaust), the logic of controller 20 can monitor a temperature runawayand adjust accordingly.

With reference to operation block 260, if no change is needed to asecondary fuel or secondary air command, then the commands can simplypass along to fuel flow device 22 and/or air device 23.

In some embodiments, the basic mode of operation 230 described above canfurther use oxygen sensors at the exhaust inlet 24 and dischargelocation 18 to estimate minimum secondary air using a method similar tothe temperature error formula. In some embodiments, the basic mode ofoperation 230 can be used as an alternate method, for example, ifanother method and its required sensors fail to operate.

With reference to FIGS. 9 and 11, in some embodiments a dynamic mode ofoperation 232 can be used instead of, or with, the basic mode ofoperation 230. With reference to operation block 262 of FIG. 11, in thedynamic mode of operation 232, the controller 20 can collect ambientsensor data from sensors 204, such as that obtained in the basic controlmode 230.

With reference to operation block 264 in FIG. 11, the controller 20 cancollect information from the sensors 202 and 204 about not only thetemperature of the incoming untreated exhaust at inlet 24, but also theoxygen level of the incoming untreated exhaust at inlet 24. Thecontroller 20 can also collect not only information about thetemperature of the exhaust discharged at exhaust pipe 18, but also theoxygen level of the exhaust discharged at exhaust pipe 18.

With reference to operation block 266 in FIG. 11, the controller 20 cancompare the temperature values it reads from the sensors with apre-loaded table of temperature set points. These temperature setpoints, along with information about the temperature and construction ofthe tube assembly 12 shell, can be used to determine a temperatureerror, as described above.

Based on the temperature error obtained above, and with reference tooperation block 268 in FIG. 11, the controller 20 can use a compositelambda function to calculate a desired composite lambda (e.g. desiredmixture of secondary fuel, secondary air, and untreated exhaust in thetube assembly 12) to provide a chemical environment to complete thecombustion process at a minimum temperature and maximum use of oxygen.The dynamic mode of operation 232 can use the oxygen sensor andtemperature sensor information in a proportional and derivative controland therefore fewer iterations can be needed to determine an appropriateamount of secondary fuel and secondary air. Furthermore, in someembodiments, the dynamic mode of operation 232 can be responsive tochanges in exhaust emission constituents of the engine, and can adjustthe composite lambda function accordingly to address such changes.

With reference to operation block 270, in order to provide a smootherresponse (less overshoot or undershoot), the controller 20 can use ratefeedback in the dynamic mode of operation 232. For example, thecontroller 20 can adjust the rate of rise and fall for the desiredcomposite lambda, providing a control over incoming engine exhausttransients while minimizing potential overshoot or undershoot of thedesired discharge temperature at exhaust pipe 18.

Over time, it is possible for a sensor in the system 10 to drift ordegrade in its output, resulting in possible errant commands from thecontroller 20. With reference to operation block 272 in FIG. 11, thecontroller 20 can adjust to compensate for steady-state errors in thesystem 10 by integrating the control signals and driving any bias out ofthe control logic. The dynamic mode 232 can thus not only provide for amore timely, accurate response to changing engine conditions, but canalso help to reduce secondary fuel usage.

With reference to FIG. 9 and to operation block 252 of FIG. 11, in anair-fuel control portion of combustion control 216, the controller 20can use a lambda/AFR function to separate the composite lambda valuefrom operation block 250 into secondary fuel and secondary air valuesneeded to maintain a desired composite lambda and temperature set pointsin the tube assembly 12.

With reference to operation block 254 of FIG. 11, the separatedsecondary fuel and secondary air values can then be communicated toinitial fuel and initial air command functions that use feedback fromfuel device 22 and air device 23, for example, to produce F′ command andA′ command signals (corresponding to secondary fuel and secondary aircommands, respectively).

With continued reference to FIGS. 9 and 11, and in particular tooperation block 256 of FIG. 11, in the thermal control portion ofcombustion control 216, the fuel and air commands can be fed to athermal control function that watches over the operation to guardagainst runaway commands and runaway temperatures, such as for exampleas described above with respect to the basic operation mode 230.

With continued reference to decision block 256 in FIG. 11, thecontroller 22 can monitor the discharge temperature at exhaust pipe 18,as well as other sensors, to determine if appropriate changes areoccurring (e.g. if the system is operating within the desiredtemperature set points), or if there is any type of temperature runaway.

With reference to operation block 258, if changes are needed to thesecondary fuel and air commands, a change direction logic can calculateappropriate changes and modify the fuel, F command and air command, Acommand.

With reference to operation block 260, if no change is needed to asecondary fuel or air command, then the commands can simply pass alongto fuel device 22 and/or air device 23. In some embodiments, the commandto the fuel device 22 in the dynamic mode can result in adjustment ofthe fuel delivery from a full spray to intermittent dosing in theinjector head 14.

As described above, the system 10 and methods of use can be incorporatedwith engine applications, including but not limited to those of avehicle, truck, or other device. In some embodiments of the system 10,the system 10 can include emissions control or operational performanceneeds that extend sensory information beyond that of the preferredembodiment to include one or more sensors and or transducers for, butnot limited to, the following: displacement of linear or angularposition of one or more dimensions or terrestrial positioning (e.g.,global positioning system), speed/rpm, acceleration, non-contactingmagnetic, ultrasonic, vibration, volumetric or mass flow metermeasurements, gas concentration measurements (other than the lambdasensor), static or dynamic force or torque measurements, andelectromagnetic (such as optoelectronic) measurements. In someembodiments the system 10 can acquire system data from existingapplication interfaces.

Although these inventions have been disclosed in the context of certainpreferred embodiments and examples, it will be understood by thoseskilled in the art that the present inventions extend beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the inventions and obvious modifications and equivalentsthereof. In addition, while several variations of the inventions havebeen shown and described in detail, other modifications, which arewithin the scope of these inventions, will be readily apparent to thoseof skill in the art based upon this disclosure. It is also contemplatedthat various combinations or sub-combinations of the specific featuresand aspects of the embodiments can be made and still fall within thescope of the inventions. It should be understood that various featuresand aspects of the disclosed embodiments can be combined with orsubstituted for one another in order to form varying modes of thedisclosed inventions. Thus, it is intended that the scope of at leastsome of the present inventions herein disclosed should not be limited bythe particular disclosed embodiments described above.

1. A system for reducing engine exhaust gas pollutants comprising: atube assembly comprising: an injector head; a plurality of chambers, atleast one of the chambers coupled to the injector head, the plurality ofchambers further comprising at least one component for directing a flowof mixture inside the tube assembly; a discharge exhaust pipe coupled toone of the chambers; a heat exchanger coupled to the plurality ofchambers; an untreated exhaust inlet coupled to the heat exchanger; afuel flow device operatively coupled to the injector head; an air deviceoperatively coupled to the injector head; and a controller configured tocommunicate with the fuel flow device, the air device, and the injectorhead.
 2. The system of claim 1, wherein the injector head comprises afuel injector nozzle and an igniter, a secondary fuel inlet, a secondaryfuel outlet, and a secondary air inlet.
 3. The system of claim 2,wherein the fuel nozzle is configured to adjust fuel delivery from afull spray to an intermittent spray.
 4. The system of claim 1, whereinthe fuel flow device is configured to direct secondary fuel into theinjector head, and the air device is configured to direct secondary airinto the injector head.
 5. The system of claim 4, wherein the secondaryfuel is from the same source as the engine's fuel.
 6. The system ofclaim 1, wherein the at least one component comprises a helical statorcomprising a rim dam and at least one radially spaced angled vaneconfigured to direct the flow of mixture in a helical pattern throughthe tube assembly.
 7. The system of claim 6, wherein the flow of mixturecomprises a burning mixture of secondary fuel injected by the injectorhead, secondary air injected by the injector head, and untreated exhaustdelivered from the engine through the untreated exhaust inlet.
 8. Thesystem of claim 1, wherein the heat exchanger comprises a plurality oftubes configured to direct a portion of untreated exhaust from theuntreated exhaust inlet to one of the plurality of chambers and to raisethe temperature of the portion of untreated exhaust.
 9. The system ofclaim 8, wherein the temperatures is raised by approximately 350 degreesF.
 10. The system of claim 8, wherein at least one of the tubes iscovered with a catalyst.
 11. The system of claim 10, wherein thecatalyst comprises a poison-resistant lean NOx catalyst.
 12. The systemof claim 1, wherein the plurality of chambers comprise a mixing chamber,a combustion chamber, and a reaction chamber.
 13. The system of claim 12wherein the mixing chamber comprises a plurality of openings on an innershell, and an outer shell which forms a passageway to the openings. 14.The system of claim 12, wherein the mixing chamber is connected to theinjector head, and the length-to-diameter ratio of an inner tube of themixing chamber is less than three.
 15. The system of claim 12, whereinthe mixing chamber diameter and internal overall flow resistance issized to maintain a back pressure that matches an engine's operatingcharacteristics.
 16. The system of claim 1, wherein a diameter of theuntreated exhaust inlet is sized based on the exhaust pipe diameter, amaximum exhaust volumetric flow rate in the tube assembly, and anallowable backpressure in the tube assembly.
 17. The system of claim 1,wherein the controller is in communication with a plurality of sensors.18. The system of claim 17, wherein the plurality of sensors comprise atleast one ambient sensor located outside of the tube assembly, at leastone exhaust temperature sensor located adjacent the untreated exhaustgas inlet, and at least one discharge temperature sensor locatedadjacent the discharge pipe.
 19. The system of claim 1, wherein thecontroller is configured to control an amount of secondary air andsecondary fuel entering the tube assembly from the fuel flow device andair device in order to maintain a desired discharge temperature at thedischarge pipe.
 20. The system of claim 1, wherein the controllercomprises a microprocessor.
 21. The system of claim 1, wherein thesystem is configured to be retrofitted onto existing diesel-poweredequipment.
 22. The system of claim 21, wherein the existingdiesel-powered equipment comprises a motor vehicle.
 23. A device forreducing exhaust emission pollutants comprising: a plurality of chambersin communication with an engine exhaust source and a discharge pipe, theplurality of chambers comprising components configured to manipulate anexhaust flow inside the chambers and form timed heated chemicalenvironments for the combustion and chemical reaction of chemicalpollutants.
 24. The device of claim 23, wherein the device is configuredto reduce the amount of nitrogen oxides, particulate matter, unburnedhydrocarbons, and partially-burned combustion products in the engine'suntreated exhaust through a combination of heating and cooling in theplurality of chambers.
 25. The device of claim 23, wherein the chemicalenvironments are configured to induce oxidation and reduction reactionseven when the exhaust flow is lean.
 26. The device of claim 23, whereinthe components comprise helical stators configured to control exhaustflow residence time within the plurality of chambers, and to direct theexhaust flow in a helical pattern through the plurality of chambers. 27.The device of claim 26, wherein the helical stators each comprise a rimdam, a plurality of angular vanes, and a plurality of openings betweenthe angular vanes.
 28. The device of claim 23, wherein the heatedchemical environments comprise temperature zones in the plurality ofchambers ranging from 800° F. (700 K) to 2300° F. (1533 K).
 29. Thedevice of claim 23, wherein the heated chemical environments comprise athermal mixing environment, a high temperature combustion environment, aheat exchanger cooling environment, and a discharge cooling environment.30. The device of claim 23, wherein the device comprises aright-circular long metal tube and an injector head, and wherein anigniter in the injector head is actuated until a flame detector detectsheat.
 31. The device of claim 23, wherein the length and diameter of theinjector head are determined by a maximum exhaust mass flow rate in thedevice.
 32. The device of claim 23, wherein one of the plurality ofchambers comprises a heat exchanger, and another of the plurality ofchambers comprises a mixing chamber.
 33. The device of claim 32, whereinthe heat exchanger comprises a plurality of tubes connecting an engineexhaust inlet to the mixing chamber.
 34. The device of claim 32, whereinthe heat exchanger is configured to both cool the exhaust flow in theplurality chambers, and heat untreated exhaust moving through the tubes.35. The device of claim 32, wherein the heat exchanger has a rectangularcross-section, and comprises a plurality of tubes.
 36. The device ofclaim 32, wherein one of the plurality of chambers further comprises areaction chamber configured to complete high-temperature combustion ofthe exhaust flow prior to the exhaust flow entering the heat exchanger.37. A method of reducing exhaust gas pollutants in an engine's exhaust,comprising: providing an assembly comprising: an injector head; aplurality of chambers, at least one of the chambers connected to theinjector head, the plurality of chambers comprising at least onecomponent for directing a mixture of flows inside the tube assembly; adischarge exhaust pipe connected to one of the chambers; a heatexchanger connected to the plurality of chambers; an untreated exhaustinlet connected to at least one of the heat exchanger and injector head;a controller in communication with the injector head; directinguntreated exhaust from the engine to at least one of the injector headand heat exchanger; directing secondary fuel and secondary air into theinjector head; igniting the secondary fuel; directing the ignitedsecondary fuel and secondary air into the plurality of chambers;directing the untreated exhaust from at least one of the injector headand heat exchanger into the plurality of chambers to form the flow ofmixture inside the tube assembly; treating the untreated exhaust bycombusting pollutants in the flow of mixture in the plurality ofchambers; cooling the mixture of flow in the plurality of chambers toreduce nitric oxides mixture of flow; and discharging the mixture offlow out the discharge exhaust pipe.
 38. The method of claim 37, whereinthe controller estimates fuel and oxygen levels in the untreatedexhaust, as well as fuel and oxygen levels in the discharged mixture offlow, and adjusts the amount of secondary fuel and secondary air beingdelivered to the injector head in order to maintain a desired dischargetemperature at the discharge exhaust pipe.
 39. The method of claim 37,wherein the controller maintains a pre-determined overall air/fuel massratio in the plurality of chambers.
 40. The method of claim 37, whereinthe controller is responsive to changes in untreated exhaustconstituents.
 41. A basic control method for controlling secondary fueland related air sources in a system which reduces engine exhaust gaspollutants, the basic control method comprising: providing an assemblycomprising: an injector head, a plurality of chambers connected to theinjector head and a discharge exhaust pipe, an untreated exhaust inletconnected to the plurality of chambers, a controller in communicationwith the injector head, at least one ignition device, at least oneambient sensor, and at least one temperature sensor adjacent the exhaustinlet and at least one temperature sensor adjacent the discharge exhaustpipe; collecting temperature, humidity, and pressure data from the atleast one ambient sensor and at least one temperature sensors; comparingthe obtained temperature data with predetermined values of temperatureset points in the controller, and based on the set points, determining atemperature error; calculating a desired composite lambda, the compositelambda representing a total air and fuel ratio inside the plurality ofchambers; separating the desired composite lambda and producingsecondary fuel and secondary air commands which direct the amount andrate of delivery of the secondary fuel and secondary air into theplurality of chambers to be mixed with untreated exhaust; and monitoringthe discharge temperature of the mixture at the discharge pipe andmodifying the secondary fuel and secondary air commands.
 42. A dynamiccontrol method for controlling secondary fuel and related air sources ina system which reduces engine exhaust gas pollutants, the dynamiccontrol method comprising: providing an assembly comprising: an injectorhead, a plurality of chambers connected to the injector head and adischarge exhaust pipe, an untreated exhaust inlet connected to theplurality of chambers, a controller in communication with the injectorhead, at least one ignition device, at least one ambient sensor, and atleast one temperature sensor and oxygen sensor adjacent the exhaustinlet and at least one temperature sensor and oxygen sensor adjacent thedischarge exhaust pipe; collecting physical and chemical data oftemperature, humidity, and pressure from the at least one ambient sensorand at least one temperature sensors; comparing the obtained temperaturedata with predetermined values of temperature set points in thecontroller, and based on the set points, determining a temperatureerror; calculating a desired composite lambda, the composite lambdarepresenting a total fuel and air ratio inside the assembly; adjustingthe rate of rise and fall for the desired composite lambda in order tominimize potential overshoot or undershoot of a desired dischargetemperature at the discharge exhaust pipe; adjusting the desiredcomposite lambda to compensate for steady-state errors; separating thedesired composite lambda and producing secondary fuel and secondary aircommands which direct the amount and rate of delivery of the secondaryfuel and secondary air into the plurality of chambers to be mixed withuntreated exhaust; and monitoring the discharge temperature and oxygenlevels and modifying the secondary fuel and secondary air commands; andmonitoring the secondary air commands for chamber cooling.
 43. A devicefor reducing exhaust emission pollutants comprising: a plurality ofchambers in communication with an engine exhaust source and a dischargepipe, the plurality of chambers configured to create timed chemicalenvironments, and wherein at least two types of chemical reactions occurwithin the plurality of chambers.
 44. The device of claim 43, whereinthe at least two types of chemical reactions comprise oxidation ofcarbon monoxide and hydrocarbon particles, and reduction of nitricoxides.
 45. A method of timed chemical heating and cooling of exhaustpollutants comprising: introducing untreated exhaust flow into aplurality of chambers; introducing a combination of burning fuel and airinto the chambers to form a mixture with the untreated exhaust flow;monitoring the cooling of chambers; and holding the mixture for apredetermined period of time within the plurality of chambers.
 46. Themethod of claim 45, wherein the predetermined period of time comprises arange of 50 to 1000 milliseconds.
 47. The method of claim 45, whereinparticulate matter inside the mixture is held between 20 to 200milliseconds within a single chamber of the plurality of chambers.